The QSK19 Fuel System
2. The QSK19 fuel system is the newest in fuel technology from Cummins. The QSK19 fuel system offers infinitely variable injection timing using a simple, efficient design, with injection pressures beyond any current Cummins fuel system.
Applications
3. Currently, the QSK19 fuel system is being used on the New QUANTUM System K19 (QSK19) engine which is intended for heavy-duty industrial applications. In the future, Cummins will bring the efficiency of the QSK19 fuel system to other eng'i"ne platforms as well.
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The QSK19 fuel system features a mechanically actuated, open nozzle type injector......and using the latest generation of Cummins electronic controls, provides precise fuel management and infinitely ~ variable injection timing.
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The QSK19 Fuel System Components
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The QSK19 fuel system can be divided into:.Hydro-mechanical components
.Electronic control system components
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Hydro-Mechanical Components
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Let's start by looking at the hydro-mechanical components.8.
This schematic provides an overview of thehydro-mechanical system of the QSK19 fuel system. 1. Fuel filter head and fuel filter element
2. Fuel pump
3. Fuel control valve assembly 4. Fuel manifolds
5. QSK19 injector 6. Fuel cooler
Fuel filters
('19. Fuel flow from the supply tank is directed to the dual fuel filter head. The fuel filters have water separators and elements that filter down to 10 microns. Water separator elements are mandatory as the actuators in the control valve body are sensitive to water. The maximum inlet restriction at the filters is 4 inHg with a clean filter and 8 inHg with a dirty filter.
Fuel Pump components
10. From the filters, fuel flow is directed to the inlet of the gear pump. The fuel pump is a version of the current PT fuel pump family. The gear pump generates the system flow and pressure. The fuel inlet is on the side of the gear pump housing.
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11. From the gear pump outlet, the fuel flows through the filter screen and then to either the pump outlet or the governor assembly. The filter screen is utilized to prevent any pump debris from reaching the fuel actuators. The governor assembly regulates the gear pump output, providing variable fio~and pressure to match engine RPM.
12. The governor assembly vents or spills all excess fuel back through a check valve to the gear pump inlet. The check valve maintains fuel pump housing pressure. The regulated flow output from the gear pump is directed to the PT pump outlet. A check valve in the outlet port controls back flow when the engine is not running.
The PT pump does not contain throttling or AFC capabilities.
13. The PT pump was selected because it provides excellent pressure characteristics over the complete RPM range. ~
Control valve assembly
14. The core of the QSK19 fuel system is the control valve assembly. Fuel flow produced by the pump is delivered to the control valve assembly. The assembly consists of a shut down solenoid valve, two fuel actuator valves, and two fuel pressure sensors. The ECM mounts on the front of the assembly housing.
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15. The control valve assembly has one fuel inlet port and two outlet ports. Each outlet port is controlled by a separate actuator.
.The fuel rail actuator controls the fuel required for com-bustion.
.The timing fuel actuators controls the fuel necessary to control injector timing.
16. The QSK19 fuel system utilizes the Pressurerrime concept like the PT fuel system. The PT is completely mechanical and relies on mechanically adjusted flow areas to regulate fuel pressure. The QSK19 fuel system, however, controls fuel pressure by electronically adjusting flow areas of the actuators.
17. For an example of the PressurefTime concept, let's consider the following: With equal sources of pressure connected to passages of different flow areas, if both systems are allowed to flow for the same amount of time, more fluid will be collected in the container of the system with the larger flow area.
Therefore, with fluid pressure and flow time held constant, the flow area determines the quantity of fluid collected.
18. If passages of equal flow area are now connected to unequal sources of pressure and the time the fluid is allowed to flow is held constant, more fluid will be collected in the container of the system that has a greater source of pressure.
Thus, if the flow area and flow time are held constant the pressure determines the amount of fluid collected.
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19. Finally, if passages of equal flow area are connected to equal sources of pressure, the time the fluid is allowed to flow will determine the amount of fluid collected.
Thus, if the flow area and fluid pressure are held constant, the time de\ermines the amount of fluid collected.
These three illustrations provide an excellent example of the Pressure!Time concept used in the QSK19 fuel system rail and timing systems.
20. The control valve assembly receives fuel flow from the fuel pump. Inside the control valve assembly, the fuel flow divides to supply both control systems.
21. The control system that maintains fuel rail pressure consists of a rapid restart fuel shut-off valve, fuel rail~ actuator and fuel rail pressure sensor. Fuel flows through the rapid restart fuel shut-off valve first and then to the fuel rail actuator.
Rail pressure control
22. The actuator is an electronically controlled spool type control valve. The coil receives a PWM signal from the ECM. Depending on the signal from the ECM, the spool will move to the left uncovering the inlet port and allowing fuel flow.
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23. The fuel rail pressure sensor monitors this pressur.e and sends this information to the ECM. The fuel rail actuator valve has a maximum flow rate of 1000 pounds per hour.
Timing control system
24. The control system that maintains the timing rail pressure consists of a timing rail actuator and timing rail pressure sensor. Fuel pressure in the timing rail is controlled by the timing rail actuator which is also controlled by the ECM. The timing rail pressure sensor monitors the pressure, and sends this information back to the ECM. The timing rail actuator has a maximum flow rate of 1500 pounds per hour.
25. Fuel flows from the control valve body through the fuel transfer tubes to the fuel manifold.
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There are two manifolds, the front manifold serving
cylinders 1 through 3 and the rear manifold 4 through 6.
Each manifold has three passages: timing rail, fuel rail, and
drain.
Drillings in the cylinder head intersect with the fuel manifold. Timing fuel and rail fuel pass through the cylinder head to the injector. Drain fuel from the injectors passes through the cylinder head to the fuel manifold. We will talk about the QSK19 fuel system injectors later in the program.
Rail and Timing pressure
26. In applications where the fuel supply tank is higher than the engine, a check valve prevents drain fuel from flowing back into the system when the engine is not in operation.
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Fuel cooler
27. The correct fuel temperature is critical to the proper operation of the QSK19 fuel system. Thus, a fuel cooling radiator is mandatory. Drain fuel from the fuel manifold is directed to a thermostat at the cooler. At 89. F the ,
( thermostat i~ closed and no fuel flows through the cooler. 8t-.90. F the" thermostat starts to open and is fully opened at
1 QA:F. This causes all drain fuel to flow through the cooler. ( Although heat is dissipated from the fuel by the supply tank, ' the use of the fuel cooler insures positive temperature .,/ control. The typical drain fuel flow rate is 2 GPM. Also, the
cooling radiator can have no more than a 5 PSI restriction.
The QSK19 Fuel System Injector
28. The QSK19 fuel system injector shares many design features with PT and CELECT. It represents, however, the next generation in technology. The new QSK19 fuel system injector will be capable of up to 35,000 psi of fuel injection pressure in the future. Currently pressures are in the 25,000 psi range.
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29. The new injector has three individual moving sections: .The lower plunger,
.The timing plunger .The upper plunger
All of the plungers are coated with Titanium Nitride to resist scuffing wear and provide maximum service life.
Lower section
30. The lower part of the injector is very similar to the PT injector. The plunger and nozzle are shaped like the PT. The fuel supply, metering, drain and check valves are also similar to the PT system.
One important difference is that the lower barrel and nozzle are one piece. This design eliminates high pressure joints.
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31. The open nozzle design of the injector provides the ideal rate and shape of injection. A slow start of injection allows a slower burn at the beginning of combustion for reduced combustion noise. The sharp end of injection, eliminating secondary injection, provides reduced hydro-carbon emission. For every injection cycle, the stroke of the lower plunger is 10 mm.
Timing section
32. The QSK19 fuel system provides infinitely variable injection timing. The timing is varied by controlling fuel pressure to the injector timing section. The timing section consists of a balance orifice, timing plunger, and deflector ring. The timing plunger is positioned in the barrel bore below the upper plunger.
Upper section
r 33. The upper section of the injector consists of the barrel,
.spring housing, return spring, upper plunger, top stop cap
and plunger link.
Theory of operation
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35. We will start the injection cycle with the cam follower on the outer base circle. All three plungers are in contact with each other, as the camshaft rotates, the follower rolls toward the inner base circle which causes all three plungers to retract. When the lower plunger retracts far enough, the Jail feed port is uncovered and fuel is PT (Pressure- T}:ne) metered through an orifice into the cup.
36. Remember from PT theory, the "P" is rail pressure and "T" is the time that the feed port is uncovered. The time will depend on engine speed.
Timing and rail metering
37. The Rail pressure will be controlled electronically and can be as high as 290 psi or as low as 2 psi. The lower plunger is in its fully retracted position when the spring retainer contacts the ledge.
38. The cam follower continues to roll toward the inner base circle, allowing the timing and upper plungers to continue moving upward. When the upper plunger retracts far enough, it uncovers the timing feed port and fuel is also PT metered through an orifice into the timing chamber.
End of timing metering
39. As the cam follower starts up the injection ramp of the camshaft, the upper plunger will move down and close the timing feed port to end Timing Metering. The fuel that metered into the timing chamber is now trapped between the upper plunger and the timing plunger.
40. The amount (volume) of fuel metered into the timing chamber determines the separation between the upper and timing plungers. The amount of separation determines the effective length of the injector plunger. This length determines when injection will start. Changing the overall plunger length changes the start of injection.
The separation between the plungers varies from a
minimum of 2 mm to around 9 mm. This separation is
41. The trapped fuel becomes a solid link and all three ( plungers move down together. As the lower plunger moves,
the rail feed port is also closed.
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43. Therefore, if the pressure in the timing chamber is 12,500 PSI, pressure in the cup can be as high as 25,000 PSI. This reduction ratio allows the injector train to operate with minimum stress and wear yet still produce extremely high injection pressures.
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Injection begins
44. The downward velocity of the plungers will increase as the follower continues up the injection ramp of the camshaft. When the pressure in the cup exceeds the pressure in the cylinder, injection begins.
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End of injection
45. Injection ends as the lower plunger makes contact with the nozzle seat. At approximately the same time, the groove in the timing plunger aligns with the groove in the barrel, opening the spill port. The timing fuel then spills as the upper plunger continues its stroke.
46. During this spill process, the drilling in the timing plunger regulates the fuel pressure in the timing chamber to keep a load on the lower plunger. This pressure is necessary to prevent the lower plunger from lifting before mechanical contact occurs between the upper and timing plungers. A spill ring is positioned over the spill port because the timing fuel spilling from the chamber is under pressure, . The spill ring acts as a pressure deflector to prevent damage to the injector bore in the cylinder head from the continual release of high pressure fuel.
47. During the last 5 mm of upper plunger travel, the nose on the bottom of the upper plunger engages with the port in the timing plunger. The clearance between the two parts acts as an additional flow restriction on the fuel in the port. This additional restriction keeps pressure on the lower plunger while the rest of the timing fuel is spilling.
48. This feature is needed to ensure that the lower plunger does not unseat during the transition from the ramp to the nose of the camshaft lobe.
Mechanical crush
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49. As all of the timing fuel spills from the chamber, the plungers will make mechanical contact. The downward travel of the injector train will continue creating a mechanical crush condition on the lower plunger. This ensures that the plunger remains sealed in the nozzle during combustion.
System operation overview
50. By now we should have a good grasp of the fueling and timing concepts involved with QSK19 fuel system. So, let's take a close look at how electronics control the engine fueling.
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51. The QSK19, like the other Cummins electronic engines, is commanded by an Electronic Control Module (ECM). The QSK19 fuel system ECM contains the latest technology from Cummins Electronics. It has two micro processors to process and manage the data necessary to operate the engine and,-systems. It also contains 2MB of memory to store calibration and fault data.
52. The ECM's main task is to manage the fuel control system that operates the engine. The ECM samples all inputs, processes the data, and outputs signals to the rail and timing control actuators many times each second. The ECM can make changes to rail and timing pressures very quickly, responding instantly to the slightest variations in operating and environmental conditions.
53. For example, look at when the operator opens the throttle to increase engine speed. The ECM will consider the , request for increased engine speed, the actual engine ! speed, an all other inputs. It will then compare this data to its calibrated data to determine the appropriate signal changes.
54. If additional engine speed is allowed, the ECM then outputs the appropriate signals to the fuel rail control actuator to increase engine RPM. If this increase in engine speed requires a change in injection timing, the ECM will output the appropriate signals to the timing control actuator as well.
Electronic subsystems
55. From the previous overview, we should have a good idea of the basic system operation. Let's now look at each subsystem and the components that make up these systems. We'll start with the inputs.
System Inputs
56. The ECM utilizes input information to determine engine fuel
and timing pressures, or, more simply, to operate the
engine. The inputs are divided into the following:
.Sensor inputs
.Switch inputs
.Operator inputs
.Feedback inputs
Temperature sensors
57. There are two temperature sensors. The temperature
sensors provide critical temperature information to the
ECM. The temperature sensors are:
.Coolant temperature sensor
.Intake manifold temperature sensor
Coolant temperature sensor
58. The coolant temperature sensor is mounted in the thermostat housing. The information this sensor obtains is utilized by the ECM to help make decisions for timing and engine protection.
Intake manifold temperature sensor
59. The intake manifold air temperature sensor is mounted in the aftercooler housing and measures air temperature after the cooler core. The information this sensor obtains is utilized by the ECM to help make decisions for timing and
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engine prot~ctlon.
Pressure sensors
60. There are six pressure sensors that provide critical
information to the ECM. The pressure sensors are:
.Fuel
rail pressure sensor
.Fuel
timing pressure sensor
.-' Oil pressure sensor
.Coolant
pressure sensor
.Boost
pressure sensor
.Ambient
air pressure sensor
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Fuel rail pressure sensor
61. The fuel rail pressure sensor is mounted in the fuel control valve assembly and measures actual fuel pressure in the rail supplying the injectors.
Fuel timing pressure sensor
62. The fuel timing pressure sensor is also mounted in the fuel control valve assembly. It measures actual fuel pressure in the rail supplying the timing chambers.
Oil pressure sensor
63. The oil pressure sensor is mounted in a main rifle port above the ECM. It measures main system oil pressure. The information this sensor obtains is utilized by the ECM to makde decisions for engine protection.
Coolant pressure sensor
64. The coolant pressure sensor is located in the oil cooler housing. It measures coolant system pressure. The information this sensor obtains is utilized by the ECM to make decisions for engine protection.
Boost pressure sensor
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65. The boost pressure sensor is mounted in the aftercoolerhousing and measures air inlet pressure after the turbocharger. The information this sensor obtains is utilized by the ECM to determine accurate engine fueling.
Ambient air pressure sensor
66. The ambient air pressure sensor is mounted on the fuel control valve assembly below the ECM. The ECM utilizes the information received from the sensor to make decisions for engine protection. In high altitude operation. the engine is derated to prevent turbocharger overspeed.
Engine speed sensor
67. The engine speed sensor is located in the back of the front gear housing. It detects 24 raised pads on the back of the camshaft gear and sends signals to the ECM. The ECM processes these signals to determine engine speed.
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The sensor'has a dual signal output providing two separate signals to the ECM. Even if one signal is lost, the engine will continue to operate.
Switch inputs
68. There can be two system switches. They are: .Idle validation switch
Idle validation switch
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69. The idle validation switch is located in the throttle pedal assembly. It provides a confirming signal to the ECM as to the position (released or depressed) of the throttle pedal.
Coolant level switch
70. The coolant switch monitors the coolant level in the radiator top tank. If the fluid level drops below a predetermined point the switch will open, indicating a low fluid level to the ECM. The information this sensor obtains is utilized by the ECM to make decisions for engine protection.
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Feedback inputs
71. In addition to monitoring the fuel and timing pressure sensors to determine actual pressures, the ECM also monitors the current returning from the rail and timing control actuator valves. This feedback information provides confirmation of correct valve operation.
Operator inputs
72. The two main inputs from the operator are the key switch and the throttle. The position of the key switch determines the state of engine operation (on of off), and the position of the throttle determines the desired engine speed.
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Possible feature inputs
73. The other possible feature inputs modify engine operation
and are provided by switches. The intermediate speed
control feature will be discussed later. Some of these inputs are:
Alternate droop
Intermediate speed control Alternate torque
Alternate low idle speed
System outputs
74. There are six system outputs. Three of the outputs control the fuel rail, timing rail, and fuel shutdown functions. The fuel and timing control actuator valves are spool type valves. The spools are controlled by an electromagnetic device which is commanded by the ECM. The ECM produces the following signals:
.Fuel control actuator valve signal -PWM (Pulse Width Modulation) duty cycle
.Timing control actuator valve signal -PWM duty cycle .Fuel shutoff -power to the shutoff solenoid valve
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75. The remaining three outputs are for system information.
.Diagnostic lamps -fault communications
.Datalink -system programming
.Tachometer -output signal for tachometer operation
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QSK19 Fuel System Governors
76. The QSK19 fuel system is capable of providing two types of engine governing, Automotive type and Variable speed VS type. Both of the governor types are programmable through calibration.
Automotive governor
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77. The automotive governor maintains engine speed based on throttle position and engine load. The percent throttle determines the available engine torque. With the throttle in a fixed position, engine speed will drop as the load is increased.
INSITE -Features and Adjustable Parameters
78. The automotive governor would be selected from the Features screen in the Features and Adjustable Parameters function of INSITE.
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79. In the Performance Data screen, the parameters shown can be set for the automotive governor. Breakpoint 1 speed is the RPM at which the fuel curve transitions to high idle droop. Droop at Breakpoint 1, is the percentage droop setting at this RPM. Droop at Maximum Throttle, is the percentage droop setting at maximum high idle RPM. Droop at Minimum Throttle. Is the percentage droop setting at idle RPM. Engine Speed, provides idle speed setting.
Variable speed governor
80. The variable speed governor varies engine speed in direct relationship to throttle position. The governor tries to hold the engine speed constant at a fixed throttle position.
81. The variable speed governor would also be selected from the Features screen in the Features and Adjustable
Parameters function of INSITE.
82. In the Performance Data folder, the same parameters as were set for the automotive governor can also be set for the variable speed governor.
Intermediate speed control
83. The QSK19 fuel system offers up to two intermediate speed control settings. In an intermediate speed control mode, the engine speed is controlled to a preprogrammed value regardless of throttle position.
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84. A separate droop percentage can be set which applies to all switched intermediate speeds and will be in force while the engine is in intermediate speed control.
Low idle adjustments
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85. The low idle speed setting is set by calibration. It can however be modified by the Increment/Decrement switch. The speed can be increased or decreased by toggling the increment, decrement switch.
Engine Protection Features
86. The QSK19 fuel system features an engine protection
system that is designed to prevent engine damage due to
prolonged exposure to extreme conditions. The ECM
monitors the following systems to provide this protection:
.Coolant level
.Coolant temperature
.Oil pressure
.Intake manifold temperature
INSITE -Features and Adjustable Parameters
87. Engine Protection can also be enabled or disabled from the Features screen in INSITE's Features and Adjustable Parameters function.
Engine Protection Shutdown is also enabled or disabled from this screen.
When the ECM det~cts a out-of-bounds condition, a series of protective actions are initiated. The action initiated is dependent on the severity and duration of the condition. The protective actions are as follows:
.Engine protection lamp is lit and a fault is logged .Engine torque and [or] speed is derated
.Engine shutdown is activated Engine Protection Lamp
88. The first level of protection is the Engine Protection Lamp. When a parameter being monitored goes out-of-bounds, the ECM lights the engine protection lamp and logs a fault. The engine protection lamp is the operator's first indication that a system parameter is out-of-bounds.
Torque and speed derate
89. After turning on the engine protection lamp, the ECM starts recording elapsed time and monitors the severity of the event. If either duration or severity exceed a programmed value, the ECM initiates a torque and/or speed derate. After a derate is initiated, the ECM will continue to monitor both duration and severity and will shutdown the engine if the condition is not corrected. The engine shutdown feature can be overridden through OEM calibration options.
Altitude derate
90. The QSK19 fuel system will automatically derate the engine at a predetermined altitude. The ECM determines altitude by monitoring ambient air pressure and, using calibration tables, determines the altitude derate.
Overspeed protection
91. If the engine speed exceeds a predetermined RPM, the ECM will remove power from the fuel shutdown solenoid valve stopping fuel flow to the system. It will also log a fault and continur. recording engine data. When the engine speed drop~. to a predetermined RPM, the ECM will apply power to the shutdown solenoid to restart the engine. The ECM can be programmed to deny engine restart if a predetermined number of shutdowns has occurred. This prevents the use of the engine when an intermittent problem exists.
Diagnostics
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Engine protection lamp
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93. The engine protection lamp is used to warn the operator of the following conditions:
.Coolant/intake temperature out of range. .Oil/ambient pressure out of range.
.Coolant level out of range. The protection lamp will light and stay on as long as any of these conditions exist. .Fuel temperature out of range.
Warning/Stop engine la\S
94. The yellow warning lamp is used to warn the operator that a component or system has logged a fault. The vehicle can continue operation, but the conditions must be corrected as soon as possible. The red engine stop lamp is used to warn the operator that a major system problem has occurred. The vehicle should be shutdown as soon as possible.
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Diagnostic switch
95. The diagnostic switch is used in conjunction with the yellow and red fault lamps to display active fault codes. With the engine not running and the key switch in the "ON" position, move the diagnostic switch to the "ON" position to check for active fault codes.
Flash code sequence
96. The fault code flash process sequence begins with the WARNING (yellow) lamp flashing once. There will be a short one to two second pause and then the STOP (red) lamp will flash out the three digit fault code. There will be a short pause between each digit in the code. After the code has been flashed, the yellow lamp will flash and then the .~ red lamp will again flash out the same fault code. The , system will continue flashing this same fault code until the diagnostic switch, increment/decrement switch, or key switch is activated.
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97. To display the next active fault code, move the increment/ decrement switch to the increment position. If there is another active fault code, it will flash out as before. If there is only one active fault code, that code will flash out again. I,.
98. If there are multiple active fault codes, use the increment! decrement switch to move through the list. The increment position will move forward through the fault list and the decrement position will move backward through the list. If you move completely through the list of codes, you will come back to the first code again.
Program end
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